Non-thermal pasteurization of lipid emulsions by combined supercritical carbon dioxide and high-power ultrasound treatment.

Supercritical carbon dioxide (SC-CO2) is a novel method for food pasteurization, but there is still room for improvement in terms of the process shortening and its use in products with high oil content. This study addressed the effect of high power ultrasound (HPU) on the intensification of the SC-CO2 inactivation of E. coli and B. diminuta in soybean oil-in-water emulsions. Inactivation kinetics were obtained at different pressures (100 and 350 bar), temperatures (35 and 50 °C) and oil contents (0, 10, 20 and 30%) and were satisfactorily described using the Weibull model. The experimental results showed that for SC-CO2 treatments, the higher the pressure or the temperature, the higher the level of inactivation. Ultrasound greatly intensified the inactivation capacity of SC-CO2, shortening the process time by approximately 1 order of magnitude (from 50 to 90 min to 5-10 min depending on the microorganism and process conditions). Pressure and temperature also had a significant (p < 0.05) effect on SC-CO2 + HPU inactivation for both bacteria, although the effect was less intense than in the SC-CO2 treatments. E. coli was found to be more resistant than B. diminuta in SC-CO2 treatments, while no differences were found when HPU was applied. HPU decreased the protective effect of oil in the inactivation and similar microbial reductions were obtained regardless of the oil content in the emulsion. Therefore, HPU intensification of SC-CO2 treatments is a promising alternative to the thermal pasteurization of lipid emulsions with heat sensitive compounds.

Kinetic improvement of olive leaves' bioactive compounds extraction by using power ultrasound in a wide temperature range.

In this study, the effect of temperature and ultrasonic application on extraction kinetics of polyphenols from dried olive leaf was investigated. Conventional (CVE) and ultrasonic-assisted extraction (UAE) were performed at 10, 20, 30, 50 and 70°C using water as solvent. Extracts were characterized by measuring the total phenolic content, the antioxidant capacity and the oleuropein content (HPLC-DAD/MS-MS). Moreover, Naik's model was used to mathematically describe the extraction kinetics. The experimental results showed that phenolic extraction was faster in UAE (ultrasonic-assisted extraction) than in CVE (conventional extraction), being extraction kinetics satisfactorily described using Naik model (include VAR>98%). Besides, the total phenolic content, the antioxidant capacity and the oleuropein content were significantly (p<0.05) improved by increasing the temperature in both CVE and UAE. Oleuropein content reached 6.57±0.18 being extracted approximately 88% in the first minute for UAE experiments.

Ultrasonic characterization of the fat source and composition of formulated dry-cured meat products.

The aim of this work was to test the feasibility of using ultrasonic measurements to estimate the fat content and identify the fat sources used in formulated dry-cured pork meat products. For that purpose, dry-cured sausages were prepared using different fat sources (two Iberian pork backfats, Iberian lard, and sunflower oil) and contents (fat content from 3% to 17% wet basis) and characterized by measuring the ultrasonic velocity (at 2 degrees C, 6 degrees C, 10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C), fatty acid profile, thermal behavior, and composition. The fatty acid composition affected the melting behavior of the sausages, which also involved different ultrasonic velocities, depending on the fat source used for the sausage formulation. Significant (p < 0.05) linear relationships were established between the ultrasonic velocity and the percentage of melted fat, by means of which the sausage batches were differentiated according to the fat source used. The ultrasonic velocity temperature dependence allowed the determination of the fat content (explained variance 96.1%) by measuring the ultrasonic velocity in the dry-cured sausages at 2 degrees C and 25 degrees C and using a semi-empirical equation. Therefore, the ultrasonic measurements could be considered as a reliable tool for the characterization and differentiation of formulated dry-cured meat products with different fat sources and contents.